Speech-feature discrimination-testing measures the auditory capacity to discriminate features of the speech signal such as formant frequency transition and the frequency composition of noise bursts. A program of research is proposed to study application of these measures in diagnosis, prediction, and alleviation of the problem of speech discrimination loss in sensorineural hearing impairment. Clinically feasible measures of discrimination-masking by the first formant (F1) will be developed. Individual values of these measures will be evaluated for predicting low-frequency suppression settings for simulated hearing-aid amplification. The criterion measures will be word reception scores and received sentence intelligibility, both measured after adequate listener experience with the amplification settings. Data will be collected from moderate-to-severely impaired listeners, both young adult and elderly. Results from the elderly will be deposited with the Temporal Bone Bank for possible future correlation with the peripheral auditory-anatomy findings.